Suction muffler for a hermetically enclosed refrigerant compressor

ABSTRACT

The invention concerns a suction muffler ( 1 ) for a hermetically enclosed refrigerant compressor with a housing ( 2, 3 ) having, between an inlet ( 10 ) and an outlet ( 11 ), a first muffling chamber ( 8 ) in the flow direction and a second muffling chamber ( 9 ) in the flow direction, an insert ( 7 ) being arranged between the muffling chambers ( 8, 9 ), the insert ( 7 ) having a passage ( 18 ) that connects the muffling chambers ( 8, 9 ) to each other. It is endeavoured to obtain a certain degree of freedom when positioning the suction mufflers in the case of the compressor. For this purpose, the insert ( 7 ) has a tube ( 12 ) that is led through the second muffling chamber ( 9 ), one end of the tube ( 12 ) being led through the housing ( 2 ), the other end opening into the first muffling chamber ( 8 ).

CROSS REFERENCE TO RELATED APPLICATION

Applicant hereby claims foreign priority benefits under U.S.C. § 119 from German Patent Application No. 10 2008 014 328.6 filed on Mar. 14, 2008, the contents of which are incorporated by reference herein.

FIELD OF THE INVENTION

The invention concerns a suction muffler for a hermetically enclosed refrigerant compressor with a housing having, between an inlet and an outlet, a first muffling chamber in the flow direction and a second muffling chamber in the flow direction, an insert being arranged between the muffling chambers, the insert having a passage that connects the muffling chambers to each other.

BACKGROUND OF THE INVENTION

Such a suction muffler is, for example, known from DE 199 23 734 C2. The housing has an upper part and a bottom part. The insert is fixed between the upper part and the bottom part. In the bottom part the inlet is arranged, which opens via an inlet channel into the first muffling chamber. With a space, the inlet channel extends into a tube channel, which forms the passage in the insert. The tube channel again extends into an outlet channel, a space being provided between the tube channel and the outlet channel, the space connecting the outlet to the second muffling chamber.

Such an embodiment is known from DE 101 28 225 C1. Also here a flow path is provided, which extends straightly from an inlet channel to an outlet channel and is connected to both muffling chambers.

Such suction mufflers for refrigerant compressors have proved to be efficient. They reduce noise that occurs because of pressure pulsations during suction of the refrigerant gas by the refrigerant compressor.

The suction muffler is usually arranged at the cylinder head of the refrigerant compressor. The refrigerant compressor is arranged in a hermetically enclosed case and is usually supported in relation to the case by means of springs. The case comprises an oil sump serving as reservoir, for lubrication of the moving parts of the compressor with oil. During compressor operation and for a certain time after standstill a part of the refrigerant is dissolved in the oil. Because of the high pressure in the case volume, this mixture remains after standstill of the system. The mixture will not be separated until the system is restarted. The vacuum arising in the case volume will separate the refrigerant from the oil, which shows in a short foaming of the refrigerant-oil mixture.

There is a tendency towards building smaller compressors. The smaller the compressor is, the more utilisation space is available in a refrigeration appliance, for example a refrigerator or a freezer. One method of reducing the dimensions is to reduce the height of the refrigerant compressor.

With the reduction of the height of the compressor, however, the suction muffler comes relatively close to the oil sump, meaning that there is a risk that to a higher degree oil from the oil sump will be drawn into the suction flow of refrigerant. However, a too heavy load of oil in the refrigerant gas should be avoided.

SUMMARY OF THE INVENTION

The invention is based on the task of ensuring a certain freedom for the positioning of the suction muffler in the compressor case.

With a suction muffler as mentioned in the introduction, this task is solved in that the insert has a tube that is led through the second muffling chamber, one end of the tube being led through the housing, the other end opening into the first muffling chamber.

With this embodiment, it is possible to shift the inlet from the bottom side of the housing and to arrange it in a different position. If, for example, the inlet can be positioned at the upper side of the housing or at least in the upper half of the housing, the suction muffler can be arranged substantially closer to the oil sump than it would be the case with an inlet in the lower half of the suction muffler. The inlet and the outlet can then be arranged in the same half of the suction muffler, for example both in the upper half, or even at the upper side of the housing. In this case, the housing can even be permitted to dip somewhat into the oil sump. The suction muffler is then made as a “schnorkel” suction muffler. By means of the tube, the refrigerant gas sucked in is led through the second muffling chamber. In this connection, the tube path for the refrigerant gas surrounded by the tube is sealed in relation to the second muffling chamber, so that no impermissible mixing between the gas sucked in and the gas in the second muffling chamber can take place. Also, sound waves from the second muffling chamber cannot right away trespass into the tube path, so that a sound propagation through the tube is avoided.

Preferably, the housing has an outwardly projecting first tube connection, the tube being led through said connection. As the suction muffler is a component of a refrigerant compressor, which is manufactured in large numbers, the accuracy of the parts, from which the suction muffler is manufactured, can only to a certain degree be increased. It is therefore assumed that a small clearance will remain, when the tube is led through the housing. This clearance causes that a small opening occurs between the tube and the housing, for example in the form of an annular gap. If a tube connection is used, the axial length of this annular gap will be increased, so that the annular gap can provide a substantial flow resistance, and thus also a resistance against the escape of sound waves from the second muffling chamber to the outside. As this opening, that is, the annular gap, opens outwards, that is, towards the inside of the compressor case, the efficiency of the suction muffler is practically not negatively influenced. Small openings or holes, opening towards the outside, change the acoustic properties of the suction muffler only to a small degree.

Preferably, the housing has an inwardly guided, second tube connection, through which the tube is led. Thus, the sealing “path” between the outside of the tube and the inside of the housing is extended. The resulting axial length of the annular gap provides a relatively good sealing, which prevents refrigerant gas from the second muffling chamber from escaping to the outside. Thus, also a sound propagation towards the outside is kept small.

Preferably, the second tube connection has a length, which corresponds to at least 75% of the smallest distance between the insert and the housing in the area of the second tube connection. Preferably, the second tube connection will even be so long that it practically reaches the insert. The larger the length of the second tube connection is, the better is the sealing achieved between the second tube connection and the tube.

Preferably, the insert has a jacket tube, which surrounds the second tube connection, at least on part of its length. Together, the jacket tube and the tube form an annular gap, into which the second tube connection of the housing projects. The inner diameter of the jacket tube is adapted to the outer diameter of the second tube connection. The inner diameter of the second tube connection is adapted to the outer diameter of the tube, small tolerances being acceptable. This embodiment provides some kind of labyrinth seal, which provides a relatively good protection against an escape of refrigerant gas from the second muffling chamber and thus a propagation of sound waves from the second muffling chamber to the outside. Further, after a certain operation time, a certain amount of oil will gather between the jacket tube and the second tube connection, which further improves the sealing between the jacket tube and the second tube connection.

It is preferred that the jacket tube has a length, which corresponds to at least 75% of the shortest distance between the insert and the housing in the area of the second tube connection. Thus, a relatively large part of the length of the second tube connection will be surrounded by the jacket tube. The larger the length, the better the sealing.

Preferably, the tube projects through the insert. This means that a certain length of the tube extends into the first muffling chamber. In a manner of speaking, this can be utilised to guide the suction refrigerant gas into the first muffling chamber. This guiding can be utilised to achieve improved muffling properties.

Preferably, the passage between the muffling chambers is formed by a tube channel, which is arranged in the insert and projects over the insert on both sides. A tube channel as such is known from DE 101 28 225 C1 mentioned in the introduction. With the tube channel it can be provided that the refrigerant gas is guided when passing from the first muffling chamber into the second muffling chamber.

It is particularly advantageous, if the tube channel and an outlet channel are arranged in series in the flow direction along the same axis. Between the tube channel and the outlet channel, a space exists, which ensures a connection to the second muffling chamber. Sound waves occurring because of pulsations can then propagate into the second muffling chamber without penetrating to the outside. However, the refrigerant gas from the first muffling chamber will be sucked into the refrigerant compressor with relatively little resistance.

Preferably, the tube has an opening, which lies opposite a curved bottom wall of the housing. The suction refrigerant gas, which flows in through the tube, can then be redirected by a vortex formation causing only small losses. The curved bottom wall then leads the suction refrigerant gas to the tube channel and thus in the direction of the outlet.

Preferably, in the first muffling chamber the housing has a gas guiding wall, which surrounds the tube on a part of its circumference. If the suction muffler is mounted so that it is partly submerged into the oil sump of the case, it is difficult to provide oil outlet openings in the suction muffler. Therefore, the gas guiding wall ensures that practically no hollows or recirculation zones are present, in which larger oil amounts could gather. On the contrary, the gas guiding wall ensures that oil sucked in by the refrigerant gas will eventually also be taken out of the suction muffler by the refrigerant gas. A small amount of oil in the suction muffler, however, is not harmful.

It is preferred that the curved bottom wall extends into a guiding surface, which is at least partly arranged in parallel with the axis. If oil should gather, it is driven by the refrigerant gas along the bottom wall to the guiding surface and from here into the passage, so that it reaches the outlet.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention is explained on the basis of a preferred embodiment in connection with the drawings, showing:

Only FIGURE is a schematic cross-section through a suction muffler.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A suction muffler 1 has a housing with an upper part 2 and a bottom part 3. The upper part 2 has a circumferential flange 4, which is fixed to a circumferential flange 5 on the bottom part, for example by bonding or welding. Between the two flanges 4, 5 an additional flange 6 of the insert 7 is arranged and fixed, which separates the housing into a first muffling chamber 8 and a second muffling chamber 9. The order of the muffling chambers 8, 9 here refers to a flow direction from an inlet 10 for the refrigerant to an outlet 11 for the refrigerant.

The upper part 2, the bottom part 3 and the insert 7 are made of a plastic material with poor heat conductivity, for example PBTP.

The insert 7 has a tube 12, which is in the present case made in one piece with the insert 7. However, the tube 12 can also be connected to the insert 7 in other ways.

The tube 12 is led through the second muffling chamber 9 and through the upper part 2 to the outside. In the area, where the tube 12 projects from the upper part 2, the upper part has an outwardly extending first tube connection 13, whose inner diameter does, with certain manufacturing-caused tolerances, correspond to the outer diameter of the tube 12.

The outwardly extending first tube connection 13 extends inwardly into a second tube connection 14, which projects inwardly from the upper part 2 and extends into the second muffling chamber 9. The inner diameter of the second tube connection 14 corresponds to the outer diameter of the tube 12. The second tube connection 14 extends approximately up to the insert 7. At least, it has a length, which corresponds to at least 75% of the smallest distance between the insert 7 and the upper part 2 in the area of the second tube connection 14 and thus of the tube 12.

The insert 7 has a jacket tube 15 that extends in parallel to the tube 12. The inner diameter of the jacket tube 15 corresponds to the outer diameter of the second tube connection 14. In this way, a labyrinth-like seal occurs between the second muffling chamber 9 and a chamber outside the suction muffler 1. Also if, due to existing tolerances, small gaps should appear between the tube 12, the first tube connection 13, the second tube connection 14 and the jacket tube 15, refrigerant gas wishing to escape from the second muffling chamber 9 to the outside will be guided over a relatively large length, so that a relatively good tightness is ensured. As long as refrigerant gas from the second muffling chamber 9 cannot escape to the outside, practically no sound waves with large amplitudes can escape to the outside in this way.

At the end facing the upper part 2, the jacket tube 15 has a bevel 16, so that an annular chamber with a triangle-shaped cross-section is formed. Oil that is carried into the second muffling chamber 9 by the refrigerant gas and settles at the second tube connection 14, then runs into the gap between the jacket tube 15 and the second tube connection 14, thus further contributing to the tightness.

The outlet 11 is arranged at an outlet channel 17. The insert 7 has a passage 18, which is arranged in a tube channel 19. The tube channel 19 is also made in one piece with the insert 7. The tube channel 19 lies on the same axis as the outlet channel 17. Refrigerant gas flowing through the passage 18 and receiving a certain direction because of the tube channel 19 can pass into the outlet channel 17 without experiencing large losses. A space 20 is provided between the tube channel 19 and the outlet channel 17, pulsations in the second muffling chamber 9 being able to propagate via said space 20.

An extension 21 of the tube 12 projects into the first muffling chamber, that is, it extends somewhat over the insert 7. The tube 10 has an opening 22, which lies opposite to a curved bottom wall 23. In continuation of the tube 12 the bottom part 3 has a gas guiding wall 24. Refrigerant flowing into the first muffling chamber 8 through the tube 12 is guided along the gas guiding wall 24. The cross-section of the gas guiding wall 24 corresponds to a part of the tube 12. The refrigerant gas led to the curved bottom wall 23 may here emit a part of the oil contained in it. The refrigerant gas drives this oil to a guiding surface 25, which is, at least partly, arranged in parallel to the axis of the passage 18 or the tube channel 19. The refrigerant gas flowing into the passage 18 again takes along the oil from the guiding surface 25, so that it is passed on the circuit. The risk that oil will settle inside the suction muffler 1 is relatively small.

The design described provides an easy way of ensuring that a transition from the first muffling chamber 8 to the second muffling chamber 9 only takes place via the passage 18. Further “leakages” do not exist.

With regard to sound, the second muffling chamber 9 is practically closed in the outwardly direction. A “leakage channel” with a very small cross-section and a large length may exist, which extends along the outside of the tube 12. As, however, this leakage channel opens towards the outside, that is, into the inside of the compressor case, this will have practically no negative influence on the muffling properties of the suction muffler.

While the present invention has been illustrated and described with respect to a particular embodiment thereof, it should be appreciated by those of ordinary skill in the art that various modifications to this invention may be made without departing from the spirit and scope of the present invention. 

1. A suction muffler for a hermetically enclosed refrigerant compressor with a housing having, between an inlet and an outlet, a first muffling chamber in the flow direction and a second muffling chamber in the flow direction, an insert being arranged between the muffling chambers, the insert having a passage that connects the muffling chambers to each other, wherein the insert has a tube that is led through the second muffling chamber, one end of the tube being led through the housing, the other end opening into the first muffling chamber.
 2. The suction muffler according to claim 1, wherein the housing has an outwardly projecting first tube connection, the tube being led through said connection.
 3. The suction muffler according to claim 1, wherein the housing has an inwardly guided, second tube connection, through which the tube is led.
 4. The suction muffler according to claim 3, wherein the second tube connection has a length, which corresponds to at least 75% of the smallest distance between the insert and the housing in the area of the second tube connection.
 5. The suction muffler according to claim 3, wherein the insert has a jacket tube, which surrounds the second tube connection, at least on part of its length.
 6. The suction muffler according to claim 5, wherein the jacket tube has a length, which corresponds to at least 75% of the shortest distance between the insert and the housing in the area of the second tube connection.
 7. The suction muffler according to, claim 1 wherein the tube projects through the insert.
 8. The suction muffler according to claim 1, wherein the passage between the muffling chambers is formed by a tube channel, which is arranged in the insert and projects over the insert on both sides.
 9. The suction muffler according to claim 8, wherein the tube channel and an outlet channel are arranged in series in the flow direction along the same axis.
 10. The suction muffler according to claim 1, wherein the tube has an opening, which lies opposite a curved bottom wall of the housing.
 11. The suction muffler according to claim 10, wherein in the first muffling chamber the housing has a gas guiding wall, which surrounds the tube on a part of its circumference.
 12. The suction muffler according to claim 10, wherein the curved bottom wall extends into a guiding surface, which is at least partly arranged in parallel with the axis. 